Universal mobile telecommunications system (UMTS) is a 3rd generation (3G) asynchronous mobile communication system operating in wideband code division multiple access (WCDMA) based on European systems, global system for mobile communications (GSM) and general packet radio services (GPRS). The long-term evolution (LTE) of UMTS is under discussion by the 3rd generation partnership project (3GPP) that standardized UMTS.
A closed subscriber group (CSG) identifies subscribers of an operator who are permitted to access one or more cells but which have restricted access (CSG cells). A CSG cell broadcasts a CSG indicator set to true and a specific CSG identity. A CSG whitelist is a list stored in a UE containing CSG identities of the CSG cells to which the subscriber belongs.
Meanwhile, due to an in-device industrial, scientific and medical (ISM) transmitter, a 3GPP LTE radio can be interfered in case that the 3GPP LTE radio and an ISM radio coexist within the same device operating in adjacent frequencies. It may be called as in-device coexistence (IDC) interference. For example, when the LTE radio is working on band 40 and the ISM radio such as wireless local area network (WLAN) is active in a same device at the same time, the LTE radio in Rx mode is interfered by the ISM transmitter. Also, the transmission of the LTE radio can interfere the reception of the ISM/GNSS (global navigation satellite system) radio.
Generally, if a UE enters a proximity of a CSG cell on a frequency, the UE performs a handover procedure to the CSG cell. In this case, the IDC interference may occur on the frequency. Accordingly, a method for transmitting a message when a UE enters a proximity of the CSG cell on a frequency and IDC interference occurs on the frequency may be required.